This invention relates to lock mechanism for a door and, more particularly, to such a mechanism which is, for the most part, mounted externally of the door and which is actuatable on command to lock and release the door. The invention has particular utility in the context of a security lock mechanism, such as might be used in detention facilities and industrial applications.
In a detention facility, not infrequently a sliding door is provided for closing a door opening. With such a facility, it is advantageous that the door be securely locked when in its closing position, that the door also be lockable in its open position, that the door have an intermediate, partially open position where it is also capable of being locked, and that a dead latch system be incorporated in the lock mechanism inhibiting tampering with the door closed and locked in this position. The lock mechanism of the invention addresses all of these requirements, by providing that a door controlled thereby be locked at two different zones or regions with the door closed, a dead latch preventing without release of the lock mechanism, and a system which permits a door controlled thereby to be locked in a closed position, a partially open position, or in a fully open position. The lock mechanism is controlled by a power-operated means which enables the door tender to control the condition of the lock mechanism through remote controls. In a specific and preferred embodiment of the invention, such power-operated means takes the form of a fluid-operated ram and, more particularly, an air cylinder, which is readily controlled through valves and switches.
A general object of the invention, therefore, is to provide a new and improved lock mechanism mounted for the most part externally of a door which is adjustable to produce locking and unlocking of the door.
A related object is to provide such a lock mechanism which includes a dead latch inhibiting tampering to produce undesired release.
A further object is to provide such a lock mechanism which includes two locking instrumentalities functioning to lock the door in position when the door is closed.
Another object is to provide such a lock mechanism having the capability of locking the door closed, as well as in an open position and, if desired, in an intermediate position where the door is only partially open.
A further object of the invention is to provide such a lock mechanism where desired adjustments are the result of shifting one instrumentality through operation of a power-operated means, such as an air cylinder.